1. Field of the Invention
The present invention relates to a descent control device for use in descending from a higher elevation to a lower elevation along a rope or cable, and more particularly, to a rope mounted, descent control device including a deadman brake.
2. Description of the Prior Art
A descent load lowering device in the form of a small cylindrical drum about which a rope is wound to provide a descent braking function is disclosed in U.S. Pat. No. 4,550,801, issued Nov. 5, 1985, to William E. Forrest, for "Personal High Rise Evacuation Apparatus." The device shown in the patent to Forrest includes end plates on each end of a cylindrical drum with apertures on each end plate through which a rope is threaded and wound in two or more turns around the drum. The lower end plate is provided with one or more arcuate tapered slots opening into the rope receiving aperture for engaging and binding the rope in order to provide a brake. The operator grasps and moves the free untensioned end of the rope along a tapered slot to vary the rate of descent or stop it altogether by tensioning and holding the rope in the narrow end of the arcuate tapered slot.
Tapered slots are ancient and well known in the art of releasably fastening ropes, lines and cables, such as in the nautical field where tapered slots are widely used for engaging and retaining ropes, lines, hausers and cables. The use of cylindrical capstans for holding and providing a mechanical advantage for tightening ropes is also old and well known. Likewise, a variety of fire escape devices utilizing a rope wound around a cylinder are old and well known. See, for example, U.S. Pat. No. 771,251 issued Oct. 4, 1904 to O. Howe for "Fire-Escape"; U.S. Pat. No. 386,237 issued July 17, 1888 to T. Budd for "Fire Escape"; U.S. Pat. No. 1,115,603 issued Nov. 3, 1914 to J. Smith for "Fire Escape"; and U.S. Pat. No. 536,866 issued Apr. 2, 1895 to C. FitzGerald for "Fire Escape."